This invention relates to a transfer case differential mechanism for a four-wheel drive vehicle, and more particularly to a dual-planetary differential incorporating torque-splitting capability in a compact and simplified manner.
The prior art contains a large number of four-wheel drive vehicles that have utilized planetary differential gearing systems. The U.S. Pat. 3,420,121 to R. W Stieg discloses a torque dividing spur gear differential for multiple driven rear axles on a vehicle. The Stieg patent shows a spur gear differential in which each set of planetary pinions on the differential carrier comprise a reducing gear train between the differential side gears. Another planetary torque proportional differential is disclosed in U. S. Pat. No. 3,899,938 to E. R. Crabb. This patent provides a torque transfer system for a two-axle vehicle including a planetary torque proportioning differential for proportioning input torque between first and second coaxially disposed, relatively rotatable output shafts which are operatively connected to first and second axles, respectively.